This would mangle messages if the first byte of a message ended up
as the last byte returned by a read() call - it would read beyond
the end of the buffer, decide the message was damaged, and then run
off into the message data looking for a new delimiter. Sometimes
that would work (only dropping one message), but sometimes it would
run into data that happened to look like a message start but
actually wasn't, and then try to interpret that, leading to completely
bogus message data being read.
Fixes#29.
Added some code to enable the user to configure unit selection in a more
detailed fashion. you can now select either metric or imperial, or both,
and even set which one of those should be displayed first.
* check the username fits the format expected by adduser;
* don't allow root;
* if the user exists, don't try to create it; usually, this is
harmless, but it fails if the user exists with a UID outside the
normal range for system users.
Fixes#24.
Track NUCp when we compute positions.
Do speed checks when we have an updated position with the same or worse NUCp
before accepting the new position. Don't do speed checks on new postions if
they improve NUCp - assume that the new position is better.
Include NUCp in aircraft.json
Gather stats on reasons for rejecting CPR data due to range/speed check failures.
Expire old positions if we have had no updates for 60 seconds.
Closes#16, closes#17.
We already do this check when scoring a message for the demodulator,
but there are other paths that can feed us a message so also do the
check in the main decode path.
This is possible now that the SBS output doesn't rely on the global block timestamp;
the output will look like this:
MSG,8,111,11111,4AC954,111111,2015/02/08,17:57:53.917,2015/02/08,17:57:53.936,,,,,,,,,,,,0
MSG,7,111,11111,392AEB,111111,2015/02/08,17:57:53.744,2015/02/08,17:57:53.936,,15375,,,,,,,,,,0
MSG,8,111,11111,392AEB,111111,2015/02/08,17:57:53.917,2015/02/08,17:57:53.936,,,,,,,,,,,,0
MSG,6,111,11111,800387,111111,2015/02/08,17:57:53.919,2015/02/08,17:57:53.936,,,,,,,,4745,0,0,0,0
where the "receive timestamp" (first time column) goes backwards to reflect the original reception
time of the delayed message, but the "forwarded timestamp" (second time column) reflects the actual
forwarding time.
the message being emitted immediately.
Fix computation of reception time so it's more sensible (the block timestamp
is some time after reception of the _end_ of the block, not the start) - this
means that message-emission times are always later than message-reception
times in SBS output, which is a bit more sensible.
Use clock_gettime in preference to ftime.